The present invention generally relates to rotary driving mechanisms, and more particularly to a rotary driving mechanism which can selectively and rotationally drive a plurality of bodies.
Conventionally, in fast-forward and rewind modes of an apparatus such as a tape recorder, a supply reel disc and a take-up reel disc are driven by motors provided exclusively for the two reel discs or by use of pulleys, belts and a single motor. However, some of the recent tape recorders and the like employ a driving mechanism which is controlled electronically. In this case, the electronically controlled driving mechanism is switched to a desired operating state by changing the operating state of the motor or solenoid by manipulating a switch.
However, when the two motors are provided exclusively for the two reel discs, there is a problem in that it is difficult to reduce the size, weight and manufacturing cost of the apparatus. In the case of the apparatus which uses the solenoid, the coupling between the solenoid and the driving mechanism becomes complex.
On the other hand, there is another conventional driving mechanism comprising a drive gear driven by a motor, a swing lever, and an intermediate gear which is rotatably supported on the swing lever and is constantly in mesh with the drive gear. According to this driving mechanism, a pair of reel discs are selectively driven by the intermediate gear depending on the rotary position of the swing lever. This driving mechanism has a simple construction but can selectively drive two reel discs. However, this driving mechanism cannot drive another mechanism in addition to the two reel discs, and there is a problem in that an independent driving mechanism must be provided exclusively for driving the other mechanism.
Still another driving mechanism has been proposed in a Japanese Utility Model Application No. 60-54640 in which the applicant is the same as the assignee of the present application. This proposed driving mechanism is designed so that the swing lever described above is pivotally supported on an output shaft of the motor with a predetermined friction. According to this proposed driving mechanism, it is possible to effectively reduce the slippage between the intermediate gear and the reel disc when the reel disc is driven. However, it is difficult to maintain stable performance of this driving mechanism for a long period of time. Furthermore, the driving mechanism cannot drive another mechanism in addition to the two reel discs.